A US official on Friday said four American military instructors and one student in Venezuela under the bilateral programme had been told to leave the bases and schools where they were working.

"The US embassy regrets this unexpected action. The US government hopes to maintain the historical fraternal relations between the two militaries," the US embassy said.

The move marked a further deterioration in military contacts between President Hugo Chavez's government and the United States, which has sharply criticised recent arms purchases by Caracas.

"It was unexpected and no explanation was given," the US official said.

Military ties

The US army, air force and navy officers were instructing their Venezuelan counterparts in areas such as infantry tactics, flying and communications.

Since he was first elected president, Chavez has made a point of downgrading military cooperation with Washington. For example, he has refused to allow US planes to carry out anti-narcotics flights over Venezuela.

A year ago, Venezuela asked members of the US military mission to vacate liaison offices at armed forces bases in the country.